The present invention relates to a SiC-Si.sub.3 N.sub.4 composite system for special heat-resisting ceramic materials and its fabrication method. The major object of the present invention is to provide a SiC-Si.sub.3 N.sub.4 composite system for special heat-resisting ceramic materials having improved resistances to thermal shock and fracture due to thermal fatigue and its fabrication method. The special heat-resisting ceramic materials of the present invention can be produced by firing in a nitriding gas atmosphere a green compact composed of silicon powder and an organic silicon polymer containing silicon and carbon atoms as the major skeletal components such final fired compact can have the novel texture of interwoven SiC and Si.sub.3 N.sub.4 is therein fired, resulting in markedly improved physico-chemical properties such as high resistances to thermal shock, to fracture due to thermal fatigue and to oxidation.
The organic silicon polymer referred to in the present invention has been originally invented by Prof. Seiji Yajima et al, Institute of Metallic Materials, Tohoku University as a family of organic silicon polymers containing silicon and carbon atoms as the major skeletal components. It is world-widely known that Prof. Yajima et al. have invented SiC fibers derived from such organic silicon polymers. There are now many relevant papers and patent specifications available on this invention. In addition, inspired by their invention, many relevant inventions have followed concerning the composition of SiC fibers with metallic or non-metallic materials, or the utilization of the organic silicon polymer as binding material for metallic or non-metallic powder and the employment of the organic silicon polymer as the starting material for SiC fired compacts, thus opening a new field in the researches of inorganic fibers, high-strength materials and heat-resisting materials.